In effectuating the water bank program authorized by this chapter, the Secretary shall have authority to enter into agreements with landowners and operators in important migratory waterfowl nesting and breeding areas for the conservation of water on specified farm, ranch, or other wetlands identified in a conservation plan developed in cooperation with the Soil and Water Conservation District in which the lands are located, under such rules and regulations as the Secretary may prescribe. These agreements shall be entered into for a period of ten years, with provision for renewal for additional periods of ten years each. The Secretary shall, beginning in 1980, reexamine the payment rates at the beginning of the fifth year of any such ten-year initial or renewal period and before the beginning of any renewal period, in the light of the then current land and crop values, and make needed adjustments in rates for any such initial or renewal period as provided in section 1304 of this title. In addition, the Secretary shall, beginning in 1980, reexam­ine the payment rates in any agreement that has been in effect for five years or more in the light of current land and crop values and make any needed adjustments in rates. As used in this chapter, the term “wetlands” means (1) the inland fresh areas described as types 1 through 7 in Circular 39, Wetlands of the United States, published by the United States Department of the Interior (or the inland fresh areas corresponding to such types in any successor wetland classification system developed by the Department of the Interior), (2) artificially de